Packless Silencer for a Venturi Control Valve

ABSTRACT

A packless silencer for a Venturi control valve being a generally rectangular enclosed housing formed by four side walls and having an intake opening and a discharge opening. Four perforated baffles for each of the side walls are positioned inside of the housing, extend the length of the housing and are offset from the side walls to create an empty baffle space between the perforated baffles and the side walls the ends of the baffle space are covered by end caps.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This patent application claims priority from U.S. Provisional Patent Application No. 61/477,858, filed Apr. 21, 2011, which is hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a Venturi control valve that is used to control the flow of air through a duct system of a heating, ventilation, and air-conditioning (HVAC) system, and more particularly, the invention relates to a packless silencer that is closely connected to the Venturi control valve to suppress the noise created by the Venturi control valve.

BACKGROUND OF THE INVENTION

A conventional HVAC system includes a duct system for directing the flow of air into and out of an occupied space that is heated, ventilated, or cooled by the HVAC system. In order to control the flow of air through one region of the duct system, control valves may be placed within the duct system to limit the flow of air to one region or another of the occupied space. A Venturi control valve, such as that disclosed in Lorch et al. U.S. Patent Application Publication No. 2002/0162589, is conventionally used to control the flow of air through a portion of the duct system. Such a Venturi control valve provides a constant volume of air flow over a range of pressures within the duct system. Such Venturi control valves, however, generate excess noise that may be annoying to persons occupying the space that is heated, ventilated, or cooled by the HVAC system.

Conventional silencers used with Venturi control valves include Helmholtz resonator silencers, such as that disclosed in Lorch et al. U.S. Pat. No. 6,116,375, packless silencers, such as that disclosed in Ingard U.S. Pat. No. 4,287,962, and silencers packed with acoustical material, such as foam, rock-wool, fiberglass, etc. Typically, silencers for Venturi control valves are spaced away from the Venturi control valve by at least 3 feet or more.

Therefore, there is a need to suppress the noise created by the Venturi control valves where the available space around the Venturi control valve is limited.

SUMMARY OF THE INVENTION

In order to suppress the noise created by a conventional Venturi control valve within a limited space, the present invention includes an inlet silencer for the exhaust Venturi control valve or an outlet silencer for the supply Venturi control valve. The inlet silencer comprises four side walls defining a generally, rectangular inlet silencer housing with an intake opening and a discharge opening. Similarly, the outlet silencer comprises four side walls defining a generally, rectangular outlet silencer housing with an intake opening and a discharge opening. The inlet silencer, in accordance with the present invention, is directly connected to an inlet opening of the Venturi control valve, and the outlet silencer, in accordance with the present invention, is directly connected to an outlet opening of the Venturi control valve. The inlet silencer and the outlet silencer are closely coupled to the Venturi control valve, and each is no greater than 24 inches in length (in the air flow direction). Typically in the industry, 3 feet of air duct is interposed between conventional silencers and the Venturi control valve.

Moreover, the inlet silencer and the outlet silencer are packless silencers with no acoustical material, such as foam, rock-wool, fiberglass etc., installed inside the walls of the inlet silencer and the outlet silencer. Instead, the inlet silencer and the outlet silencer are each lined with perforated metal baffles spaced inwardly approximately one inch from the side walls along the full length of the silencer housing thereby creating a baffle space between the perforated baffles and the side walls. No acoustical material (insulation) is present in the baffle space between the perforated baffles and the side walls of the silencer housing. A set of reinforcing braces are placed approximately in the center of the baffle space between baffles and the side walls, and metal end caps close the ends of the baffle space adjacent the intake openings and the discharge openings of the silencers. The baffles are perforated. Typically, the perforations are in the shape of spaced round holes. Any standard perforation pattern, however, may be employed.

When compared to conventional silencers used with Venturi control valves, the closely coupled, packless inlet silencer and the closely coupled packless outlet silencer of the present invention perform as well or better than the less space efficient silencers of the prior art.

Further objects, features and advantages will become apparent upon consideration of the following detailed description of the invention when taken in conjunction with the drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a Venturi control valve with a closely coupled, packless inlet silencer in accordance with the present invention.

FIG. 2 is a side elevation view of the Venturi control valve (with the internal detail of the Venturi control valve shown in phantom) with the closely coupled, packless inlet silencer in accordance with the present invention.

FIG. 3 is an end elevation view (as seen looking in the direction opposite the air flow) of the Venturi control valve with the closely coupled, packless inlet silencer in accordance with the present invention.

FIG. 4 is a perspective view of a Venturi control valve with a closely coupled, packless outlet silencer in accordance with the present invention.

FIG. 5 is a side elevation view of the Venturi control valve (with the internal detail of the Venturi control valve shown in phantom) with the closely coupled, packless outlet silencer in accordance with the present invention.

FIG. 6 is an end elevation view (as seen looking in the direction of the air flow) of the Venturi control valve with the closely coupled, packless outlet silencer in accordance with the present invention.

FIG. 7 is a perspective view of the packless inlet silencer or the packless outlet silencer in accordance with the present invention.

FIG. 8 is a perspective view of the packless inlet silencer or the packless outlet silencer with the outside walls removed to show internal detail in accordance with the present invention.

FIG. 9 is an exploded view of the packless inlet silencer or the packless outlet silencer in accordance with the present invention.

FIG. 10 is a detailed perspective view of a corner of the packless inlet silencer or the packless outlet silencer in accordance with the present invention.

FIG. 11 is a side elevation view of the packless inlet silencer or the packless outlet silencer in accordance with the present invention showing internal detail in broken lines.

FIG. 12 is an end elevation view of the packless inlet silencer or the packless outlet silencer in accordance with the present invention.

FIG. 13 is a section view of the packless inlet silencer or the packless outlet silencer in accordance with the present invention as seen along line 13-13 of FIG. 12.

FIGS. 14A, 14B, and 14C are detailed plan views of perforation patterns that are suitable for the baffles of the packless inlet silencer or the packless outlet silencer in accordance with the present invention.

FIG. 15 is a perspective view of a second embodiment of a packless inlet silencer in accordance with the present invention.

FIG. 16 is a perspective view of the second embodiment of the packless inlet silencer with the outside walls removed to show internal detail in accordance with the present invention.

FIG. 17 is an exploded view of the second embodiment of the packless inlet silencer in accordance with the present invention.

FIG. 18 is a side elevation view of the second embodiment of the packless inlet silencer in accordance with the present invention showing internal detail in phantom.

FIG. 19 is an end elevation view of the second embodiment of the packless inlet silencer in accordance with the present invention.

FIG. 20 is a section view of the second embodiment of the packless inlet silencer in accordance with the present invention as seen along line 20-20 of FIG. 19.

FIG. 21 is a series of sketches showing alternative silencer constructions that are not in accordance with the present invention and are the subject of testing reported in Tables 1 and 2 below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning to FIGS. 1-3, a Venturi control valve 12 is conventional in construction and is used in a HVAC duct system to control the flow of air within an HVAC duct system. Particularly, the Venturi control valve 12 provides constant air flow over a range of pressure within the HVAC duct system. The Venturi control valve 12, however, may create a level of noise that may be unacceptable to occupants of space that is served by the duct system that includes the Venturi control valve 12. The Venturi control valve 12 has an inlet opening 14 and an outlet opening 16. In order to reduce noise generated by the Venturi control valve 12, the inlet opening 14 of the Venturi control valve 12 is closely coupled to an inlet silencer 20. Alternatively, with reference to FIGS. 4-6, the outlet opening 16 of the Venturi control valve 12 is closely coupled to an outlet silencer 30 in order to reduce noise created by the Venturi control valve 12.

As shown in FIG. 2, the inlet silencer 20 has an intake opening 26 and a discharge opening 28. The discharge opening 28 is closely coupled to the inlet opening 14 of the Venturi control valve 12. The length of the inlet silencer 20 is 14.25 inches in the direction of the air flow into the Venturi control valve 12, but the inlet silencer 20 may be as long as 24 inches. Similarly, as shown in FIG. 5, the outlet silencer 30 has an intake opening 36 and a discharge opening 38. The inlet opening 36 is closely coupled to the outlet opening 16 of the Venturi control valve 12. The length of the outlet silencer 30 is no greater than 14.25 inches in the direction of the air flow out of the Venturi control valve 12, but the outlet silencer 30 may be as long as 24 inches.

FIGS. 7-14 show the construction of either the inlet silencer 20 or the outlet silencer 30. For the purposes of discussion, FIGS. 7-14 will refer to the inlet silencer 20, although the description has equal applicability to the outlet silencer 30. The inlet silencer 20 comprises a generally rectangular housing 22 formed by four side walls 42 a, 42 b, 42 c, and 42 d. The four side walls 42 a, 42 b, 42 c, and 42 d are joined together to form the housing 22 by a crimped seam connection 54 shown in detail in FIG. 10. The intake opening 26 and the discharge opening 28 of the inlet silencer 20 are at opposite ends of the rectangular housing 22 and are best identified in FIGS. 11 and 13.

Perforated baffles 44 a, 44 b, 44 c, and 44 d are mounted along the full length of the inside of the inlet silencer 20 by means of intake baffle end caps 56, discharge baffle end caps 58, and intermediate reinforcing braces 48 shown in FIGS. 7, 8, 9, and 11. The baffles are spaced approximately 1 inch from the inside of each of the four side walls 42 a, 42 b, 42 c, and 42 d and thereby form an approximately 1 inch baffle space 46 (FIGS. 11 and 13) between the four baffles 44 a, 44 b, 44 c, and 44 d and the four side walls 42 a, 42 b, 42 c, and 42 d. The baffle space 46 is empty without any acoustical material or packing. The baffle space 46 has end openings adjacent the intake opening 26 and the discharge opening 28 of the inlet silencer 20. The end openings of the baffle spaces are covered by the four intake baffle end caps 56 and the four discharge baffle end caps 58 (FIGS. 8, 9, 12, and 13).

Each of the four perforated baffles 44 a, 44 b, 44 c, and 44 d may be perforated with one of the illustrative perforation patterns shown in FIGS. 14A, 14B, and 14C. The perforation patterns shown in FIGS. 14A, 14B, and 14C consist of a series of spaced triangular, rectangular, and circular holes 62. The holes 62 occupy approximately 10% of the area of each of the perforated baffles 44 a, 44 b, 44 c, and 44 d. Other hole shapes and hole patterns may perform equally well.

Table 1 and Table 2 below illustrate the performance of the silencers, either inlet silencer 20 or outlet silencer 30, in accordance with the present invention when closely coupled to a Venturi control valve 12. In the Tables, the silencer 20 or the silencer 30 in accordance with the present invention is designated “J” and is shown in the sketch below Table 2. The other silencers are shown below Table 2 and are designated A-E. The Tables also show the performance of certain competitive silencers designated XYZ. The competitive silencers were closely coupled to the Venturi control valve 12.

TABLE 1 100909 Prov Pat Coaxial Inlet_Outlet/Tables PWL, dB ref 1 picoWatt Orifice Static Octave Band Peak Silencer [CFM] H2O 2 3 4 5 6 7 NC Rating Band None 1000 1.5 77 68 67 73 69 66 59 5 A 990 1.5 72 67 59 61 64 60 51 6 B 990 1.5 65 61 58 67 64 60 53 5 C 990 1.5 65 62 56 66 64 61 52 5 D 990 1.5 65 65 60 67 64 60 53 5 E 990 1.5 68 61 60 68 65 61 54 5 990 1.5 67 62 59 56 52 51 42 5 990 1.5 66 65 60 66 62 57 52 5 990 1.5 66 62 58 54 52 51 39 5

TABLE 2 Difference in Sound Power 2 3 4 5 6 7 Delta NC A 5 2 8 12 5 7 8 B 12 7 9 6 5 6 6 C 12 6 11 7 5 5 7 D 12 3 7 6 5 6 6 E 9 7 7 5 4 5 5 J 10 6 8 17 17 15 17 XYZ Valve 11 3 7 7 7 9 7 XYZ 0 3 3 12 10 6 13 w/Silencer

FIGS. 15-20 show the construction of an alternate embodiment of an inlet silencer 120. The inlet silencer 120 comprises a generally rectangular housing 122 formed by four side walls 142 a, 142 b, 142 c, and 142 d. The four side walls 142 a, 142 b, 142 c, and 142 d are joined together to form the housing 122 by a crimped seam connection 154. An intake opening 126 and a discharge opening 128 of the inlet silencer 120 are shown in FIGS. 18 and 20.

Perforated baffles 144 a, 144 b, 144 c, and 144 d are mounted along the full length of the inside of the inlet silencer 120 by means of intake baffle rounded end caps 155, discharge baffle end caps 158, and intermediate reinforcing braces 148 shown in FIGS. 15, 16, 17, 18, and 20. The baffles 144 a, 144 b, 144 c, and 144 d are spaced approximately 1 inch from the inside of each of the four side walls 142 a, 142 b, 142 c, and 142 d and thereby form an approximately 1 inch baffle space 146 (FIGS. 18 and 20) between the four baffles 144 a, 144 b, 144 c, and 144 d and the four side walls 142 a, 142 b, 142 c, and 142 d. The baffle space 146 is empty without any acoustical material or packing. The baffle space 146 has end openings adjacent the intake opening 126 and the discharge opening 128 of the inlet silencer 120. The end openings of the baffle spaces are covered by the four intake baffle end caps 155 and the four discharge baffle end caps 158 (FIGS. 16, 17, and 19). The intake baffle end caps 155 have a rounded surface 157 that contributes to the smooth transition of the air through the intake opening 126 and into the housing 122 of the inlet silencer 120. The inlet silencer 120 further has an external end cap 156 that fits over the intake end of the housing 122. The external end cap 156 further includes a round duct connector 160 for connecting the inlet silencer 20 to the heating and air-conditioning duct of the HVAC system.

Each of the four perforated baffles 144 a, 144 b, 144 c, and 144 d are perforated with one of the perforation patterns shown in FIGS. 14A, 14B, and 14C.

As illustrated herein, the expression “closely coupled” means that the inlet silencer 20 and the outlet silencer 30 are each directly attached to the Venturi control valve 12 without any substantial length of duct without baffles 44 interposed between the Venturi control valve and either the inlet silencer 20 or the outlet silencer 30.

While this invention has been described with reference to preferred embodiments thereof, it is to be understood that variations and modifications can be affected within the spirit and scope of the invention as described herein and as described in the appended claims. 

1. A packless silencer for close connection to a Venturi control valve, the packless silencer comprising: a. an enclosed housing having side walls, an intake opening, a discharge opening, and a length; b. a perforated baffle corresponding to each of the side walls and positioned inside of the housing wherein each perforated baffle: i. extends the length of the housing; ii. is offset from the corresponding side wall to form a baffle space between the perforated baffle and the corresponding side wall; and iii. has a perforation pattern, and c. baffle end caps to seal the baffle space adjacent the intake opening and the discharge opening.
 2. The packless silencer of claim 1, wherein the baffle space is empty.
 3. The packless silencer of claim 1, wherein baffle end caps are rounded.
 4. The packless silencer of claim 1, wherein the packless silencer is less than 24 inches in length in a direction of air flow through the packless silencer.
 5. The packless silencer of claim 1, wherein the perforated baffle has an area, and the perforation pattern comprises holes in the perforated baffle that occupy approximately 10% of the area of the perforated baffle.
 6. A duct control valve comprising: a. a Venturi control valve having an inlet opening and an outlet opening; b. a packless silencer closely connected to either the inlet opening or the outlet opening of the Venturi control valve, the packless silencer comprising: i. an enclosed housing having side walls, an intake opening, a discharge opening, and a length; ii. a perforated baffle corresponding to each of the side walls and positioned inside of the housing wherein each perforated baffle: (a) extends the length of the housing; (b) is offset from the corresponding side wall to form a baffle space between the perforated baffle and the corresponding side wall; and (c) has a perforation pattern, iii. baffle end caps to seal the baffle space adjacent the intake opening and the discharge opening.
 7. The duct control valve of claim 6, wherein the baffle space is empty.
 8. The duct control valve of claim 6, wherein baffle end caps are rounded.
 9. The duct control valve of claim 6, wherein the packless silencer is less than 24 inches in length in a direction of air flow through the packless silencer.
 10. The duct control valve of claim 6, wherein the perforated baffle has an area, and the perforation pattern comprises holes in the perforated baffle that occupy approximately 10% of the area of the perforated baffle. 